I read this more as a "toy problem" - a demo on how to do caching well, than as "this data needs caching, today". i.e. a tutorial, because sooner or later you will benefit from caching.

As such I think it's a well written clear example. But you always need to bear in mind that a toy problem simple enough to demo a technique clearly, is seldom complex enough to need the technique.

To me reading this, I wonder if you also tell programmers they must avoid cache hits in L1/L2 because they simply dont need the performance, and because they don't need it they aren't allowed to use it.

My comment was specifically about this news site. What you brought up is completely different use case. I never said use my comment and apply everywhere caching can help.